1. Field of the Invention
The present invention relates to a method for bonding a protection film to one of the front and rear surfaces of a silicon wafer and an apparatus employed for the method.
2. Description of the Related Art
There are known hitherto, in a process of manufacturing a semiconductor device for an IC, an LSI or an ultra LSI, the step of bonding a protection film to the surface of a silicon wafer, and the step of cutting and polishing the rear surface of the silicon wafer obtained in the former step to make a finally obtained semiconductor device having a predetermined thickness. In the former step, as described in Japanese Patent Unexamined Application Publication No. 10-32179, a strip protection film is temporarily bonded onto a silicon wafer and then a part of the protection film which excessively extends outward of the outer periphery of the silicon wafer is cut off, i.e., so-called trimming is conducted.
However, following the recent higher integration of electronic equipment, demand for making semiconductor devices used in the equipment small in size and light in weight becomes greater and it becomes necessary to make the protection film thinner. For example, it is demanded that the thickness of a protection film which is conventionally, normally about 100 xcexcm be decreased to about 15 xcexcm. As a result, because the thinned protection film is low in physical properties, e.g., tensile strength, it is difficult to assign and bond only the protection film onto the surface of the silicon wafer neatly.
Considering this, the following protection film bonding method has been conventionally proposed. As shown in FIG. 14, a two-layer film H2 which has a reinforcement film 3 provided on the surface of a protection film 2, is assigned to a silicon wafer 1 from above, and then the two-layer film H2 is trimmed by a laser beam L along the peripheral edge of the silicon wafer 1. As shown in FIG. 15, the two-layer film H2 is joined to the surface of the silicon wafer 1 first and then the reinforcement film 3 is peeled off from the protection film 2 by a person skilled in the art, whereby the silicon wafer 1 the upper surface of which is protected only by the protection film 2 is obtained as shown in FIG. 16.
According to this method, a carrier film (not shown) is normally provided on the rear surface of the protection film 2 of the two-layer film H2. This three-layer film is designed so that the carrier film is peeled off from the protection film when the three-layer film is delivered close to the silicon wafer.
According to the above-stated conventional method, however, it is necessary to peel off one by one the reinforcement films from the protection films of silicon wafers after cutting off by the laser beam. This peel-off operation is laborious and even a person skilled in the art needs to take special care. Due to this, it is difficult to further improve productivity for a series of steps of bonding the protection film onto the silicon wafer.
The present invention has been achieved to solve the above-stated disadvantages. It is an object of the present invention to provide a method for bonding a protection film onto a silicon wafer using a three-layer film having a reinforcement film and a carrier film on front and rear surfaces of a protection film, respectively, and to provide an apparatus used for this method, capable of improving productivity for an operation for bonding the protection film onto the silicon wafer.
The invention will now be described following.
1. A method for bonding a protection film onto a silicon wafer using a three-layer film formed by providing a reinforcement film and a carrier film on a front surface and a rear surface of said protection film, respectively, said method comprising the steps of:
separating said carrier film from said three-layer film to provide a two-layer film;
bonding said protection film onto a front surface of said silicon wafer as said two-layer film;
peeling off said reinforcement film from said two-layer film bonded onto said front surface of said silicon wafer to leave only said protection film on said front surface of said silicon wafer; and
cutting off said protection film along a peripheral edge of said silicon wafer using trimming means.
2. A method for bonding a protection film onto a silicon wafer according to claim 1, wherein
after cutting off said protection film by said trimming means, a residual cutout film is collected.
3. A method for bonding a protection film onto a silicon wafer according to claim 1, wherein
after said two-layer film is bonded onto said front surface of said silicon wafer, said two-layer film is cooled by cooling means and then said reinforcement film is peeled off from said two-layer film.
4. A method for bonding a protection film onto a silicon wafer according to claim 3, wherein
said cooling means is cooled air flow injection means for injecting a cooled air flow to said silicon wafer.
5. A method for bonding a protection film onto a silicon wafer according to claim 1, wherein
said trimming means is laser beam means for applying a laser beam.
6. An apparatus for bonding a protection film onto a silicon wafer using a three-layer film formed by providing a reinforcement film and a carrier film on a front surface and a rear surface of said protection film, respectively, said apparatus comprising:
supply means for supplying said three-layer film to table means on which said silicon wafer is mounted;
separation and take-up means for separating and taking up said carrier film from said three-layer film supplied by said supply means;
assigning and separation means for inducing a two-layer film obtained by separating said carrier film from said three-layer film onto said silicon wafer, and assigning said two-layer film onto said silicon wafer;
joint means for pushing said two-layer film assigned onto said silicon wafer on said silicon wafer, and joining said two-layer film onto said silicon wafer;
peel-off means for taking up said reinforcement film while peeling off said reinforcement film from said two-layer film joined onto said silicon wafer;
trimming means for trimming said protection film obtained by peeling off said reinforcement film from said two-layer film along a peripheral edge of said silicon wafer; and
take-up means for taking up a cutout film remaining after said protection film is trimmed.
7. An apparatus for bonding a protection film onto a silicon wafer according to claim 6, wherein
said assigning and separation means, said peel-off means and said joint means are set to be able to reciprocate in a traveling direction (X) in which said cutout film travels.
8. An apparatus for bonding a protection film onto a silicon wafer according to claim 6, wherein
said peel-off means is arranged between said assigning and separation means and said joint means.
9. A method for bonding a protection film onto a silicon wafer according to claim 6, wherein
said trimming means is laser beam means for applying a laser beam.
10. An apparatus for bonding a protection film onto a silicon wafer according to claim 6, wherein
comprising cooling means for cooling said two-layer film joined onto said silicon wafer by said joint means.
11. An apparatus for bonding a protection film onto a silicon wafer according to claim 10, wherein
said assigning and separation means, said peel-off means and said joint means are set to be able to reciprocate in a traveling direction (X) in which said cutout film travels.
12. An apparatus for bonding a protection film onto a silicon wafer according to claim 10, wherein
said peel-off means is arranged between said assigning and separation means and said joint means.
13. A method for bonding a protection film onto a silicon wafer according to claim 10, wherein
said trimming means is laser beam means for applying a laser beam.
14. An apparatus for bonding a protection film onto a silicon wafer according to claim 10, wherein
said cooling means is cooled air flow injection means for injecting a cooled air flow to said silicon wafer.
The bonding method according to the present invention, which is a method for bonding a protection film onto a silicon wafer using a three-layer film having a reinforcement film and a carrier film provided on front and rear surfaces of a protection film, respectively, exhibits an excellent advantage that it is possible to further improve productivity for an operation for bonding the protection film onto the silicon wafer.
The apparatus according to the present invention can optimally realize the method.